1. Technical Field
Methods and example implementations described herein are generally directed to storage area network (SAN) storage systems, and specifically, for cloud storage systems.
2. Related Art
Network Attached Storage (NAS) systems are emerging in the enterprise IT (Information Technology) systems to store unstructured data files (e.g., document, figures, voice, movie, etc.). By using the NAS, enterprise users can share the unstructured data files on their enterprise computer network. The NAS uses standard file access protocols such as the Network File System (NFS) protocol or the Common Internet File System (CIFS) protocol to receive file read/write requests from their client computers and to reply the requested files. NAS systems can be implemented in a cloud, where storage and other functions are stored in one or more outside servers rather than on the client device.
In view of the extensibility of the network attached storage system, the related art cloud storage system was developed. The cloud storage system may include a set of one or multiple cloud gateways and one or multiple cloud storage devices. The cloud gateways are located in user sites and act as general NAS devices. Such cloud storage devices are located in external sites such as remote sites of the users or cloud services. The cloud gateways transfer the file data stored in them to the cloud storage devices according to their configurations. For example, when the total size of data stored in a cloud gateway exceeds the pre-configured threshold for total data size, the cloud gateway transfers the least accessed file into a cloud storage device that is designated as a target device for the cloud gateway. The cloud storage device then keeps mapping information between the metadata of the transferred file and the actual location of the file.
However, when the number of the cloud gateways that designate the same cloud-storage device increases, the throughput of the cloud storage device will decrease. The multiple Hyper Text Transfer Protocol/Hyper Text Transfer Protocol Secure (HTTP/HTTPS) sessions may cause congestion in a network between the cloud gateways and the cloud-storage device. The congestion reduces data transfer rate of the HTTP sessions due to the congestion control mechanism of the Transmission Control Protocol (TCP) layer. As a result, the total throughput of the cloud-storage device is reduced. Also, the multiple overlapped HTTP sessions may exhaust HTTP processing capacity of the cloud-storage device. Thus, in the same way, throughput of the cloud-storage device will be reduced.